This invention relates to foundations and supports for manufactured structures, such as mobile homes, and more particularly to a support member for manufactured structures which is capable of universal adjustability.
In their early stages of development and use, mobile homes were appropriately named because of the impermanent or temporary manner in which they were positioned. Frequently, such homes were simply set down upon suitably positioned cement blocks. In order to achieve level, or maintain level after initial positioning, various types of shims were employed between the blocks and the underframe of the home. The obvious shortcomings and dangers inherent in that kind of mounting led to numerous attempts at achieving greater stability and adjustability of levelling.
Included among the early efforts at more effective anchoring and stabilizing supports were devices employing guys, saddles and foldable arrangements which were physically a part of the mobile home. By and large, those devices were merely wedged or supported between the building structure and the ground and did little to change the temporary nature of the structure's mounting. Representative examples of such efforts may be seen in U.S. Pat. Nos. 3,606,231; 3,704,560 and 3,096,065.
Another attempt involved the use of vertically adjustable supports mounted on concrete pillars and clamped to the structural members of the building as shown in U.S. Pat. No. 3,830,024. In that scheme, tie-down straps going completely around the building were also employed to withstand high winds and gales. The tie-down straps were objectionable for esthetic reasons in addition to the fact that they imposed additional stresses and frictional wear points on the building.
More recent attempts at improved stabilization, anchoring and precision levelling have resulted in forms of mounting which have made the manufactured structures truly more permanent than mobile. This development is the outgrowth of a number of socio-economic as well as technological factors. As the number of manufactured buildings has increased, municipalities have adopted and enforced stricter building code standards regarding such matters as foundations, permanence of anchoring and ability to withstand excessive natural forces such as high winds, tornados and earthquakes. Concomitantly, lending institutions frequently have insisted that manufactured buildings literally become part of the real estate in order to qualify for mortgage financing and the like. As might be expected, the need for greater permanence has given rise to a new generation of proposed solutions.
Representative examples of the more recent proposals may be seen in U.S. Pat. Nos. 3,713,259; 4,064,668 and 4,125,975. Those patents teach devices having bottom portions that are permanently anchored or embedded in a concrete foundation which may comprise a slab or a series of piers. Cooperating with the embedded portion was a vertically adjustable member, such as a bolt or turnbuckle, carrying at its top a means for attachment to the underframe of the manufactured building. Ostensibly, those vertically adjustable and permanently anchored support devices satisfied all requirements for manufacture building supports. However, experience with their use has shown that they are less than completely satisfactory. The problems attendant the use of those devices may be said to relate to the fact that they provide only what may be termed single point support and uni-dimensional vertical adjustability.
Typically, the underframe members of a manufactured building involved in anchoring comprise a pair of steel beams (usually I-beams) or, in the case of an extra-width building, four such beams. While a steel I-beam may be assumed to be perfectly rigid, those skilled in the art understand that it is not. Of course, the manufactured building is most obviously a non-rigid structure. Indeed, the underlying concrete slab itself is non-rigid, being subject to crystalline changes and deformations of expansion and contraction caused by weathering, temperature changes and movements of the underlying soil.
Ideally, a state of equilibrium should exist between the manufactured building and its support, that is, the weight of the structure should be evenly distributed at every point along the supporting foundation. Obviously, the load at any given point in the building varies depending upon the positioning therein of furniture, appliances, etc. With the described single point support of the prior art devices, it was difficult, if not impossible, to approximate the desired state of equilibrium even in the initial placement of the building. Without the use of scientific measuring instruments, it was virtually impossible to equalize the tension between the multiple supporting devices under the building.
Assuming that a relatively stress-free and level anchoring was achieved with the prior art devices, the maintaining of that near-equilibrium state became an even more serious problem. Over any extended period of time, the alluded to changes and stresses caused by weathering, soil heave, temperature changes, building shift, and the like, invariably cause building stresses which could result in structural damage. Under such conditions, it was again virtually impossible to make the necessary adjustments for re-establishment of the equilibrium state with the prior art devices.